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UNITED STATES PATENT OFFICE.

WARREN K. LEWIS, OF NEWTON, MASSACHUSETTS, A-SSIGNOR TO THE GOODYEARTIRE & RUBBER COMPANY, OF AKRON, OHIO, A CORTORATION OF OHIO.

PREPARATION OF LAMPBLACK.

In Drawing.

T 0 all whom it may concern Be it known that I, WARREN K. Lnwis, acitizen of the United States, residing at Newton, in the county ofMiddlesex and State of Massachusetts, have invented a new and usefulImprovement in the Preparation of Lampblack, of which the following is aspecification.

My invention relates to the art of preparing lamp black or carbon blackand will be fully understood from the following specification: V

Practically all of the carbon black or lamp black of commerce is nowprepared by burning natural gas or other hydrocarbon or relatedcarbonaceous fuel with an insufficient supply of air, the flame beingchilled by impinging upon a relatively cool place which will serve asthe surface on which the free carbon resulting from the imperfectcombustion is deposited. The actual yield of lamp black by this processis relatively low as compared with the mass of carbon in the fuelburned, and it is further well recognized that for the production oflamp black of the highest grade suitable for paints having greatcovering power, the yield must be kept well below the maximum yield.obtainable by the ordinary process. I have discovered that it ispossible to largely increase the yield of carbon black nowobtained inthe combustion of, for example, a hydrocarbon gas and at the same timeeffect an improvement in the quality of the carbon. black "from thestandpoint ot' fineness or covering power, by a modification oi theconditions under which the actual combination occurs. In its broadestaspect, such modification consists in causing the combustion to takeplace in what may be described as a dilute gaseous solution ofhydrocarbon and oxygen, that is, instead of admixing with the naturalgas oxygen and nitrogen in the proportions existing in the atmosphere,the percentage of oxygen being somewhat less than. that required forcomplete combustion of the natural gas, there should be present arelatively large diluting volume of an inert gas such, for example, ascombustion gases obtained "from the combustion of natural gas, or anyother carbona- Specification of Letters Patent.

Application filed August 1.3, 1918.

Patented June 6, 1922.

Serial No. 249,640.

ceous hydrocarbon fuel. This diluting inert gas should preferably beadmixed both with the natural gas and with the air, in order to insure acompletely homogeneous atmosphere in which the combustion takes place.

Under these conditions, the individual hydrocarbon molecules areseparated by a considerable distance at the time combustion or partialcombustion takes place. By reason of this separation the number ofcontacts between the nascent carbon molecules proportionately reducedwith a resultant reduction in the size of the aggregates or particleswhich are eventually 'lormed either before or in the act of depositionupon a cool surface. The dilution has a further beneficial effect inthat there is present a relatively large envelop of the diluting inertgas around each hydrocarbon molecule, this envelop serving as a heatabsorber which rapidly reduces the temperature of the combustionproducts including the carbon. Such reduction in flame temperature,accomplished within the body of the flame itseltby the dilutingatmosphere, should, in accordance with the kinetic theory of gases, alsoreduce the mean velocity of the nascent carbon molecules and byproportionately reducing the number of contacts between molecules,retard formation of aggregates.

The beneficial effects of my improvement in the art are not qualitativealone but also quantitative, i. e., it is possible by .the practice ofthe invention to increase the yield of carbon black per cubic loot ofgas consumed. This result in part follows from the improvement inquality for, as heretofore stated, it is well known that the yield ofcarbon black may be increased considerably if the quality, i. e., degreeof fineness, be sacrificed. Since fineness of the product according tomy process is assured by principles other than percentage of oxygensupplied to the natural gas, it follows that, as com pared with the oldor known processes, it is possible to obtain a greater yield of black ofthe same quality or grade of fineness as that produced by the knownexpedient ott' reducing the percentage of oxygen with reference to thehydrocarbon. This result of increased yield may be expected to be stillfurther benefited, however, by the use of combustion gases as a diluentbecause of their containing a high percentage of carbon dioxide.Considered from the standpoint of the equilibrium or mass react-iontheory, or from the standpoint of the tendency of that reaction to takeplace which will liberate the greatest amount of heat (which principlehas in recent years been modified as involving the taking place of thatreaction which results in thegreatest degradation of energy), or fromthe standpoint of the relative affinities of hydrogen and carbon foroxygen, the presence of carbon dioxide in considerable proportions inthe atmosphere in which the combustion takes place, must inevitablyresult in the combustion of a smaller proportion of the carbon of thehydrocarbon. The degree to which this effect is obtainable is dependentto a large extent upon the flame temperature but, for the reasonsstated, the employment of combustion gas or other carbon-dioxidecontaining gas as a diluting atmosphere, is preferred.

As is suggested in the foregoing, the extent to which dilution may becarried out is limited by the flame temperature or the minimumtemperature at which flame propagation takes place. As a specificexample'of one method of carrying out my invention to produce a highyield of carbon black of a grade equal to or better than that nowproduced by the ordinarv methods, the followin may be given:

.Fhe natural gas is diluted with 4 to 5 volumes of combustion gas, whichmay be the gas obtained from the combustion of the natural. gas itselfin the process of manufacturing carbon black, or may be obtained fromany other source, and the air supply before admission to the combustionchamber is likewise diluted with l to 2 volumes of combustion gas. Sincenatural gas requires approximately ten times its own volume of air forcombustion, the total quantity of diluting combustion gas may be fromlet to times 'the volume of natural gas. Thus the total proportionalquantity of diluting combustion gas may be, in the preferred process.from 15 to 20 volumes, based on the volume of natural gas. One of the major advantages accruing from this invention is the flexibility incontrol of plant opera tions which results therefrom. By variation ofthe amount of diluent gas employed, combined with variation intemperature and amount of cooling water and the like, it is possibleeither to secure a much larger yield of black of a quality equal to thatat present obtained without sacrificingthe yield, or to combine thesetwo advantages. This makes possible wide modification of, factoryprodnet to meet market conditions without change in plant design.

\Vhile I have described in considerable detail what I believe to be theprinciples underlying and mechanism of my process, and have given onespecific example of the method of carrying out the process, it will beunderstood that my invention is not dependent upon the soundness oraccuracy of the theories which I have advanced, nor limited to the exactprocess disclosed, except in so far as such limitations are includedwithin the terms of the accompanying claims, in which it is my intentionto claim all novelty inherent in my invention as broadly as ispermissible in View of the prior art.

vVhat I claim is:

1. The improvement in the art of producing carbon black by the imperfectcombustion of hydrocarbons which comprises in ad mixing saidhydrocarbons prior tocombustion with a relatively large proportion ofinert gas sutiicient to reduce the carbon content thereof to a fractionof that of natural 2. The improvement in the art of producing carbonblack by the imperfect combustion of hydrocarbons which comprises inadmixing said hydrocarbons prior to combustion with a relatively largeproportion of diluting gas containing an oxide of carbon suiiicient toreduce the carbon content thereof to a fraction of natural gas.

3. The improvement in the art of producing carbon black by the imperfectcombustion of hydrocarbons which comprises in admixing said hydrocarbonsprior to combustion with a relatively large proportion of combustion gassutlicient to reduce the carbon content thereof to a fraction of that ofnatural gas.

4 The improvement in the art of producing carbon black by the imperfectcombustion of carbonaceous compounds, which comprises in admixing withthe air used for combustion a relatively large proportion of inert 5.The improvement in the art of, producing carbon black by the imperfectcombustion of carbonaceous compounds, which com.- prises in admixingwith the air used for combustion a relatively large proportion of inertdiluting gas containing an oxide of carbon.

(3. The improvement in the art of produc ing carbon black by theimperfect combustion of natural gas, which comprises in admixing withthe air used for combustion a relatively large proportion of combustiongas. I I I 7. The improvement in the art of producing carbon black bythe imperfect combustion of carbonaceous compounds, which consists incausing such combustion to take place in the presenceof approximately1520 volumes of inert diluting gas.

8. The improvement in the art of producing carbon black by the imperfectcombustion of carbonaceous compounds, which consists in causing suchcombustion to take place in the presence of approximately 15-20 volumesof diluting gas containing an oxide of carbon.

9. The improvement in the art of producing carbon black by the imperfectcombustion of natural gas, which consists in causing such combustion totake place in the presence of approximately 15-20 volumes of combustiongas.

WARREN K. LEWIS. Witnesses:

R. S. TROGNER, E. C. LEADENHAM.

